It creates a set of virtual audio devices named "Virtual Cables", each of them consists of a pair of the waveform input/output devices. Any application can send audio stream to an output side of a cable, and any other application can receive this stream from an input side. All transfers are made digitally, providing NO sound quality loss (a bitperfect streaming).

VAC behavior is similar to "What You Hear" (or "What U Hear", "Stereo Mix") feature of Sound Blaster Live! and Audigy. But it is only similar, not equivalent. If you simply need a function like "Stereo Mix" under Vista/Win7/Win8, there could be better to try to enable it in your audio adapter.

If more than one applications are sending audio to Virtual Cable device, VAC mixes all streams together. If more than one applications are receiving audio from Virtual Cable device, VAC distributes the same audio data among all targets.

VAC is useful to record application's audio output in real time (audio player, instant messenger or software synthesizer), or transfer a sound stream to another application processing it. You can, for example, use two or more software audio players/generators/synthesizers/sequencers to produce audio streams, sending them to Virtual Cablet device and record a mixed stream from the same Virtual Cable device, using any recording software - Audacity, Sound Forge, WaveLab, Adobe Audition (formerly Cool Edit Pro), Gold Wave, Cakewalk/Sonar, Cubase/Nuendo etc.

With an ASIO wrapper like ASIO4ALL
If you use an audio encoder application that encodes a stream coming from a sound card, you can use VAC to supply such encoder with a stream produced by other application.

You can use VAC to capture an output sound stream from the application that doesn't allow to write it into WAV file directly. Unlike Total Recorder allowing you to simply save audio stream, VAC allows to route it in real time.

If you are using some Voice Over IP (VoIP) and/or Internet Telephony applications like (Skype), you can use VAC to record your calls and conversations.

VAC needs no hardware audio card; it is a "virtual audio card" itself.

A detailed description is included into a free trial package.

Since VAC 4 is a WDM driver, there are some benefits but some (generally older) applications that use MME (waveIn/waveOut) interface can work better with the older VAC 3 version. This version also supports Windows 98/ME.

If you need to simply share your In/Out wave ports among several applications under Windows 2000 and earlier Windows versions, take a look to the Wave Clone software.

Please note that VAC is not a self-sufficient software that may work alone just under operating system control. VAC is a tool. Like hardware tools (for example, a screwdriver or a saw) that are used only together with other objects (screws or boards), VAC should be used only together with audio applications to route audio streams produced or consumed by these applications.

VAC package is distributed as a ZIP archive. Simply unpack it into an empty folder, run setup.exe application and follow the instructions displayed. If you use VAC for the first time, please read the readme.txt and vac.chm files before installation. If you have already installed previous version of VAC 4, don't forget to uninstall it before installation.

VAC is a WDM driver miniport written entirely in MS C++ using object-oriented technology. No external assembly files or additional driver development tools like VtoolsD are used.

VAC also supports a custom (proprietary) version creation to be used together with a particular application only. Each of custom versions has an unique key to identify its "native" application. This "native" application uses a special way to open the driver. Such opening way is called a "open in the native mode". When the driver is opened in native mode, it transfers audio signal without any limitations. If not, it adds a noise to the signal to prevent unauthorized usage.

Please note that custom version of VAC has the same functionality as the common version. Customization includes only unique names and unique key, not additional custom functionality.